Soil Biology

The Soil Biology Primer (USDA)

by Dr.Elaine R. Ingham

Overview

The creatures living in the soil are critical to soil quality. They
affect soil structure and therefore soil erosion and water availability. They can protect crops from pests and diseases. They
are central to decomposition and nutrient cycling and therefore affect plant growth and amounts of pollutants in the environment.
Finally, the soil is home to a large proportion of the world's genetic diversity.

Chapter
1: THE SOIL FOOD WEB

SOIL BIOLOGY AND THE LANDSCAPE

An incredible diversity of organisms make up the
soil food web. They range in size from the tiniest one-celled bacteria, algae, fungi, and protozoa, to the more complex nematodes
and micro-arthropods, to the visible earthworms, insects, small vertebrates, and plants.

As these organisms eat, grow,
and move through the soil, they make it possible to have clean water, clean air, healthy plants, and moderated water flow.

There
are many ways that the soil food web is an integral part of landscape processes. Soil organisms decompose organic compounds,
including manure, plant residue, and pesticides, preventing them from entering water and becoming pollutants. They sequester
nitrogen and other nutrients that might otherwise enter groundwater, and they fix nitrogen from the atmosphere, making it
available to plants. Many organisms enhance soil aggregation and porosity, thus increasing infiltration and reducing runoff.
Soil organisms prey on crop pests and are food for above-ground animals. continue Chapter 1- The Soil Food Web